JP2606087Y2 - Mechanical seal with bellows - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention relates to a mechanical seal having a bellows.

[0002]

2. Description of the Related Art A mechanical seal using a bellows instead of a packing such as an O-ring is known as a seal between a driven ring and a rotating shaft or a casing. This type of mechanical seal has the advantage that the driven ring is not fixed by an O-ring or the like, and the driven ring can be maintained in a good floating state.

[0003]

However, in a mechanical seal provided with a bellows, the bellows may generate self-excited vibration or resonance due to the resistance of the seal surface or the influence of the vibration of a mounting device. However, there have been problems such as the occurrence of leakage due to separation, and the generation of a large amount of leakage due to breakage of the bellows itself. Various studies have conventionally been made to solve such problems, but the mechanism of vibration generation is not clear, and at present it is impossible to take drastic measures. For example, it is presumed that the vibration due to the resistance of the sealing surface is caused by a phenomenon called stick-slip. In a simple calculation of the natural frequency, the vibration generated by the high-speed shaft rotation has a very low rotational speed range of about 150 rpm. It is difficult to predict such as occurring in An object of the present invention is to solve the above-mentioned problems of the prior art.

[0004]

In order to achieve the above object, the present invention provides a mechanical seal having a bellows for sealing a driven ring with a bellows, the mechanical seal being fixed to the driven ring and having a different amount of displacement in the axial direction of the bellows. A member having a displacement amount and the bellows are brought into contact with each other via an O-ring at a position closer to a driven ring side than a center portion of the bellows so as to restrain axial displacement of the bellows. I do.

[0005]

The bellows is brought into contact with members having different axial displacements so as to restrain the axial displacement, whereby the axial displacement is restrained. In addition, since the contact position is located on the opposite side of the driven ring from the center position of the bellows, the effect of restraining the axial displacement is large.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a half sectional view. The driven ring 2 is loosely fitted on the rotating shaft 50 so as to be able to be driven, and a sealing surface S is formed between the driven ring 2 and the fixed ring 6 attached to the casing 51 to seal the ring. A compression ring 3 is fitted to the rear end side of the driven ring 2, and the compression ring 3 is connected to a spring 5.
As a result, the driven ring 2 is pressed against the fixed ring 6 by pressing in the direction of the fixed ring 6. The spring 5
The rear end side is locked by the collar 4 fixed to the rotating shaft 50.

The bellows 1 is mounted on the inside of the compling 3 at the rear end of the driven ring 2, and the rear end is fixed on the rotating shaft 50 by the collar 4. The bellows 1 seals the space between the driven ring 2 and the rotating shaft 50. An O-ring 10 is fitted into one of the fold grooves 15 of the bellows 1, and the bellows 1 comes into contact with the compling 3 via the O-ring 10 to be restrained.

In this embodiment, the bellows 1 is provided with an O
The ring 10 is mounted. The reason will be described below.
Now, assuming that the displacement amount of the driven ring 2 in the axial direction is d as shown in the figure, since the coupling 3 is also fixed to the driven ring 2, it also has a displacement amount of d. The bellows 1 is also connected to the driven ring 2, and the amount of displacement in the axial direction is larger at a position closer to the driven ring 2, and the displacement is absorbed and becomes smaller at a position farther from the driven ring 2. That is, at the position A of the bellows 1, the displacement amount is substantially the same as that of the driven ring 2 and becomes d, but at the position C, the displacement is almost absorbed, and the displacement amount becomes almost zero.
In addition, the displacement amount is d / 2 at the intermediate position a. Therefore, in order to bring the bellows 1 into contact with the compling 3 and restrict its movement in the axial direction, it is better to make contact in the vicinity of the c-position where the difference in the displacement amount is the largest. However, if the bellows 1 is brought into contact with the compling 3 in the vicinity of the c position, on the contrary, the followability of the compling 3, that is, the driven ring 2 in the axial direction is hindered, and the contact resistance of the O-ring 10 with the compling 3 is reduced. There is a problem that adjustment is difficult. Therefore, it is best to interpose the O-ring 10 at a position between A and C where the difference between the displacement of the compling 3 and the bellows 1 is relatively large and the followability of the driven ring 2 is not excessively restricted. The O-ring 10 needs to be larger in diameter than the interval f between the fold grooves 15 of the bellows 1 so that the O-ring 10 is engaged with the fold grooves 15 so as to contact the compling 3 as shown in the figure.

In the above configuration, the O-ring 10 interposed in the fold groove portion 15 of the bellows 1 comes into contact with the inner periphery of the compling 3, and the axial displacement of the bellows 1 is regulated by the contact resistance. At the same time, vibration of the bellows 1 in the radial direction is suppressed. Therefore, self-excited vibration and resonance of the bellows 1 are suppressed, and the torsional force is buffered. Further, if the axial position of the O-ring 10 is set at an appropriate position between "a" and "c", good sealing performance can be maintained without hindering the followability of the driven ring 2.

In the above embodiment, the O-ring 10 is mounted on the fold groove portion 15 of the bellows. However, the present invention is not limited to this, and as shown in FIG.
A ring groove 11 may be provided, and the O-ring 10 may be fixed here so that the bellows 1 and the O-ring 10 are in contact with each other. Further, as shown in FIG. 3, an O-ring groove 12 may be provided on the bellows 1 side, and the O-ring 10 may be fitted therein.

FIG. 4 shows an embodiment in which the present invention is applied to a static mechanical seal in which the driven ring 2 does not rotate. In this configuration, since the compling 3 is located on the inner peripheral side of the bellows 1, the O-ring 10 is provided on the inner peripheral side of the bellows 1, and is brought into contact with the outer peripheral side of the compling 3. Reference numeral 20 denotes a sleeve.

[0012]

As described above, the present invention provides a mechanical seal having a bellows for sealing a driven ring with a bellows, the member being fixed to the driven ring and having a displacement different from the axial displacement of the bellows. The bellows, at a position on the side opposite to the driven ring than the center of the bellows, so as to restrain the axial displacement of the bellows,
Since the contact is made via the O-ring, the axial displacement of the bellows is effectively restrained, and self-excited vibration and resonance of the bellows are suppressed.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an embodiment of the present invention.

FIG. 2 is a partial half sectional view showing one embodiment of the present invention.

FIG. 3 is a partial judgment view showing one embodiment of the present invention.

FIG. 4 is a half sectional view showing another embodiment of the present invention.

[Description of Signs] 1: Bellows, 2: Driven ring, 3: Compling, 4: Collar, 5: Spring, 6: Fixed ring, 10: O-ring,
11: O-ring groove, 12: O-ring groove, 15: fold groove, 20: sleeve, 50: rotating shaft, 51: casing.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16J 15/34-15/38

Claims (2)

(57) [Scope of request for utility model registration] 1. A mechanical seal having a bellows for sealing a driven ring with a bellows, wherein a member fixed to the driven ring and having a displacement amount different from an axial displacement amount of the bellows and the bellows are connected to each other by an axis of the bellows. A mechanical seal provided with a bellows, wherein the mechanical seal is brought into contact with the bellows via an O-ring at a position opposite to a center portion of the bellows with respect to a driven ring so as to restrain directional displacement. 2. The mechanical seal according to claim 1, wherein the member is a member coupled to the driven ring.